Intravascular plasma volume and colloid oncotic pressure (COP)

Intravascular plasma volume refers to the total volume of the liquid component of blood within the circulatory system, while colloid oncotic pressure (COP) is the osmotic pressure exerted specifically by plasma proteins, primarily albumin (StatPearls, 2023). These two factors are fundamental components of the Starling forces, which govern the movement of fluid across capillary membranes; COP acts to pull fluid into the vascular space, opposing the hydrostatic pressure that pushes fluid out (Wikipedia, 2023). Maintaining an appropriate balance is essential for systemic hemodynamics, tissue oxygenation, and the prevention of interstitial edema. In medical settings, these parameters are manipulated using volume expanders to treat conditions such as hemorrhagic shock, sepsis, and severe hypoalbuminemia (PubMed, 2021). Drugs like human albumin and synthetic colloids (e.g., hydroxyethyl starch) are used to acutely increase COP and expand plasma volume. However, therapeutic targeting of these parameters requires careful monitoring due to risks of fluid overload, pulmonary edema, and potential renal toxicity associated with certain synthetic agents (NIH, 2022).

Other names

Plasma oncotic pressureColloid osmotic pressureIntravascular volumeVascular volume status

Increasing the osmotic pressure within the vascular compartment to draw or retain fluid from the interstitial space into the intravascular space.